Sailing vessels have existed for centuries. While modern sailing vessels have taken advantage of the technological progress made in materials and methods science, the fundamental operation of a sailing vessel remains the same. That is, depending on wind conditions and direction, a sail or sails must be raised, lowered, or trimmed to optimize the performance of the craft.
Modernly, as in historical times, sails are raised and lowered via a system of sheets running through pulleys or sheaves. For clarity, a pulley is a stand-alone device comprised of a housing and a sheave. The sheave is the grooved wheel that a sheet, or halyard passes across during sail raising or lowering operations. Again, for clarity, a sheet or halyard is effectively a length of rope. These halyards or sheets are referred to generally as running rigging and must be adjusted constantly to optimize operation of the vessel.
Because the running rigging is under constant strain and must be adjusted on a regular basis, wear occurs. There are numerous sources of the wear including moisture, strain from sail loading, flexing due to winching, and chaffing against stationary objects such as stays or life lines, referred to as standing rigging. The standing rigging is used to support the mast or masts and yards or spreaders. By far the worst culprit for sheet wear is chaffing. Objects such as stays or life lines are generally made from steel cable. Small protrusions, or hairs, cover the surface, so as the sheet comes in contact with standing rigging an abrading occurs which will cause an eventual separation of the sheet.
If the wear to a component of the running rigging is discovered while in port, it can be repaired prior to getting the vessel under way. But many times a sheet that appears to be in good working order at the dock will fail while the vessel in under way, far from the safety of a mooring place or dock. When this occurs the ability of the vessel to operate safely is compromised, so the separated sheet must be repaired while away from the dock.
Several methods for repairing running rigging while under way are known and in use. Historically, the splice method has been used. There are two general types of splices: the short splice and the long splice. The short splice is easiest to implement, but has the significant disadvantage of not being able to pass over a sheave due to the narrow opening of the pulley housing. If the particular sheet can be used without passing through a pulley, then this method will work adequately.
However, the vast majority of the sheet separations involve a line that must pass through a pulley. The long splice may allow such passage if the sheave is wide enough, but the long splice has the significant disadvantage of being very difficult to implement. Moreover, it takes a long time and in many cases the repair must be made in a very short period. For example, if the vessel is unable to maintain forward motion, or make way, the vessel simply drifts at the behest of the wind and current. Absent control, it is clear that the vessel can run afoul of other craft in the area or worse, run aground on the shore.
What would be desirable would be an apparatus and method that would allow a separated sheet to be repaired in a very short period of time yet allow the repaired sheet to pass through a pulley.